Impact factor measures how often articles from a journal are cited--it is sometimes used as a way to determine how "important" a journal is in its field.
The UNL Libraries subscribe to two databases that provide impact factors--Journal Citation Reports and Web of Science. However, be advised that they don't contain all journals. Journals that have only been in existence for a few years, or that have very specialized audiences, may not have impact factors at all. The impact factor might be posted on the journal's website. It might also be obtainable by writing to someone on the editorial board of the journal.
